The previous COPD surveillance report noted that rates of hospitalizations and mortality for COPD had increased from 1980 to 2000.13
However, the mortality rate in men and some age groups and hospitalization rates in both men and women have declined since 1999. Rates of physician-based office visits and ED visits for COPD from 1999 to 2010 demonstrated substantial interyear variability and showed no particular trend; however, it is encouraging that there were no increases in office visit rates or ED rates for COPD.
Because smoking is the most important etiologic driver of COPD,22
trends in the prevalence of smoking impacted many of the metrics examined in this surveillance report, although the exact temporal relationship between changes in the smoking prevalence and changes in health-care use and mortality for COPD are not well defined. Since 1965, the prevalence of smoking has decreased considerably. In 1965, 42.4% (unadjusted percentage) of adults aged ≥ 18 years were current smokers compared with 19.3% in 2010.23
The crude prevalence of smoking in 2010 was one-half that in 1965 for both men (21.5% vs 51.9%, respectively) and women (17.3% vs 33.9%, respectively). In 1999 to 2001, American Indian/Alaska Native adults had a higher age-adjusted prevalence of current smoking (30.3% in men and 34.7% in women) compared with white adults (25.1% in men and 22.2% in women),23
which may explain the increase in COPD mortality during 1999 to 2010 in that population. The prevalence of current smoking among American Indian/Alaska Native adults has since declined to 25.1% in men and 21.0% in women for 2008 to 201023
; therefore, a decline in mortality from COPD may be expected for that population in the future. However, a recent report observed that almost 39% of 15 million adults with self-reported COPD in 2011 in the United States continued to smoke.12
This large population represents an important opportunity for physician counseling and referral to smoking cessation interventions such as 1-800-QUIT-NOW.
Two broad currents influence mortality rates estimated from death certificate data: changes in the prevalence of COPD and changes in the case-fatality rate among people with COPD. Although the estimates of the prevalence of self-reported COPD from the NHIS suggest that the prevalence may have declined since 1999, the rates since 2002 have remained fairly stable. A number of treatment strategies have been shown to have the potential to reduce mortality in patients with COPD and include newer medications and evolving guidelines to treat COPD, oxygen therapy, respiratory management, pulmonary rehabilitation, and influenza vaccinations.24,25
The lag times between changes in the prevalence of COPD and the uptake of treatments and COPD mortality rates may differ. The balance of these temporal changes is likely to have a substantial impact on the trajectory of the mortality rate. With continued declines in the smoking prevalence and improved management of patients with COPD, mortality rates can be expected to decline in future years.
The generally small reduction in the age-adjusted mortality rate was limited to men. It is unclear why the mortality rate in women did not fall as well, given the decline in smoking prevalence in women since 1965. If the estimates are valid, these results suggest that research will be needed to address possible explanations for the poor progress among women. These data are consistent with the results of a study showing that the mortality rate among women with an obstructive impairment changed little in contrast to the mortality rate among men with an obstructive impairment.26
The use of spirometry is critical to establishing the diagnosis and severity of COPD. Additional tests that can help in the diagnosis include lung diffusion capacity test, chest radiograph, and arterial blood gas test. GOLD (Global Initiative for Chronic Obstructive Lung Disease) established four levels of COPD on the basis of spirometric measurements: mild, moderate, severe, and very severe.27
The results reported here should be considered in the context of several limitations. Depending on the spirometric criteria used, estimates of prevalence of COPD based on spirometry tests may be as much as double the estimates derived from self-reported information.13,28,29
Consequently, the estimates of self-reported prevalence of COPD in the current surveillance report almost certainly underestimate the true prevalence of this condition. Furthermore, not accounting for the undiagnosed percentage of adults with COPD can also potentially distort demographic comparisons. As shown in the previous surveillance report, men had a higher prevalence than women when the presence of COPD was based on spirometric criteria.13
When self-reported data were used to estimate the prevalence of COPD, however, women had a higher prevalence than men, as was also observed in the present report.
If COPD is underdiagnosed, then the mortality rates presented in the present report likely underestimate the true mortality rates from COPD.30‐32
Another factor that may contribute to underestimating COPD mortality rates is the possibility that comorbidities may displace COPD as the underlying cause of death that is reported on the death certificate.33
Assuming that underestimates of the COPD mortality rates were approximately constant during the study period, the interpretation of the direction of the trends is valid.
Race was self-reported by participants of the BRFSS and NHIS but was recorded by medical or other personnel in the other data systems. The comparability of race designations among surveys is unknown. For some data systems, such as the NAMCS, NHAMCS, and NHDS, race was missing for a large proportion of records. For example, 16% of the NHDS discharges for 2010 and 23% of NAMCS records in 2010 lacked information about the racial status of the patient. Medicare and death certificate data represented the only data that allowed trend analyses for American Indian/Alaska Natives, Hispanics, and Asian populations. Because race and ethnicity designations are subject to misclassification,34
caution is urged in interpreting racial- and ethnic-specific disparities. In the future, the BRFSS, with its large annual sample size of almost one-half million respondents, will allow trend analyses of prevalence of self-reported COPD among those racial/ethnic groups.
Since 1997, GOLD has striven to increase awareness of COPD as a major public health problem across the globe, to spur efforts to prevent this disease, and to develop guidelines to improve the diagnosis and treatment of COPD. In 2013, it released updated versions of Global Strategy for Diagnosis, Management, and Prevention of COPD.24
Several studies have reported imperfect implementation of the GOLD guidelines in clinical practice.35
Additional efforts may be needed to educate physicians about the management of this condition.
Healthy People objectives provide science-based, 10-year national objectives for improving the health of all Americans; identify nationwide health improvement priorities; and strive to engage multiple sectors (public health agencies, communities, organizations, academia, and medicine) to take actions to strengthen policies and improve practices that are driven by the best available evidence and knowledge. The Healthy People 2010 objective for COPD called for a 50% reduction in the mortality rate from COPD among adults aged ≥ 45 years at baseline in 1999 (123.9 per 100,000)36
; however, that objective was not met by 2010 (116.6 per 100,000)—possibly for many reasons described above. The new Healthy People 2020 effort37
has been expanded to include the following objectives that pertain to the evaluation and management of COPD among adults aged ≥ 45 years:
- • Reduce activity limitations among adults with COPD.
- • Reduce deaths from COPD.
- • Reduce hospitalizations for COPD.
- • Reduce hospital ED visits for COPD
- • Increase the proportion of adults with abnormal lung function whose underlying obstructive disease has been diagnosed.
The CDC and the National Heart Lung Blood Institute (NHLBI) have a formal collaboration to increase public awareness and identify critical communication, research, evaluation, and data collection needs to prevent and manage COPD. This collaboration has resulted in the annual BRFSS collection since 2011 of COPD prevalence data at state and local levels, which will enhance the COPD Learn More Breathe Better Campaign supported by the NHLBI. Such state-level and county-level data as the BRFSS, Medicare, and vital statistics can identify geographic clustering of, as well as racial/ethnic disparities in, COPD indicators to provide guidance to public health agencies in leveraging and targeting resources to those geographic areas and local populations with the greatest burden of COPD. These data will also be critical in identifying communities that will likely benefit best from awareness and outreach campaigns and in evaluating the effectiveness of public health efforts to prevent, treat, and control COPD.
COPD remains a significant source of morbidity and mortality in the United States. In 2007, chronic lower respiratory diseases constituted the fourth leading cause of death and rose to the third leading cause of death in 2008 primarily because cerebrovascular disease deaths continued a consistent decline and to a lesser extent as a result of adjustments to coding and classification.1
The data examined in this surveillance report testify to the heavy public health burden that COPD continues to levy in the United States. Prior to 1999, rates of mortality and hospitalizations had shown worrisome increases. Thus, the apparent leveling of the mortality rate and a decrease in the rate of hospitalization represent cause for cautious optimism. Future surveillance efforts will be critical to tracking the course of COPD in the United States.